-þu

• -þ, -þo, -t, -to

Partly from Proto-West Germanic *-iþu, from Proto-Germanic *-iþō; and partly from -þ +‎ -u, where the -u denotes the īn-stem of nouns, and is thus indeclinable.

• IPA^(key): /θu/

-þu f

1. forming abstract nouns from verbs, adjectives or other nouns; generally causing mutation of root or preceding vowels

o-stem

indeclinable

• Middle English: -the, -th
  • English: -th
  • Scots: -th